[Qemu-devel] [v3 09/12] block: add ability for block-stream to use node-name

[Jeff Cody]

This adds the ability for block-stream to use node-name arguments
for base, to specify the backing image to stream from.

Both 'base' and 'base-node-name' are optional, but mutually exclusive.
Either can be specified, but not both together.

The argument for "device" is now optional as well, so long as
base-node-name is specified.  From the node-name, we can determine
the full device chain.

Signed-off-by: Jeff Cody <address@hidden>
---
 blockdev.c       | 63 ++++++++++++++++++++++++++++++++++++++++++++++----------
 hmp.c            |  4 ++--
 qapi-schema.json | 17 +++++++++++----
 qmp-commands.hx  |  2 +-
 4 files changed, 68 insertions(+), 18 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 381698d..d15710a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1869,22 +1869,54 @@ static void block_job_cb(void *opaque, int ret)
     bdrv_put_ref_bh_schedule(bs);
 }
 
-void qmp_block_stream(const char *device, bool has_base,
-                      const char *base, bool has_speed, int64_t speed,
+void qmp_block_stream(bool has_device, const char *device,
+                      bool has_base, const char *base,
+                      bool has_base_node_name, const char *base_node_name,
+                      bool has_speed, int64_t speed,
                       bool has_on_error, BlockdevOnError on_error,
                       Error **errp)
 {
-    BlockDriverState *bs;
+    BlockDriverState *bs = NULL;
     BlockDriverState *base_bs = NULL;
     Error *local_err = NULL;
+    const char *base_name = NULL;
 
     if (!has_on_error) {
         on_error = BLOCKDEV_ON_ERROR_REPORT;
     }
 
-    bs = bdrv_find(device);
+    if (has_base && has_base_node_name) {
+        error_setg(errp, "'base' and 'base-node-name' are mutually exclusive");
+        return;
+    }
+
+    if (!has_base_node_name && !has_device) {
+        error_setg(errp, "'device' required if 'base-node-name' not 
specified");
+        return;
+    }
+
+    if (has_device) {
+        bs = bdrv_find(device);
+        if (!bs) {
+            error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+            return;
+        }
+    }
+
+    if (has_base_node_name) {
+        base_bs = bdrv_lookup_bs(NULL, base_node_name, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+        /* the overlay->backing_file may not always be equal to
+         * base_bs->filename, due to how relative paths are calculated */
+        base_name = base_bs->overlay ? base_bs->overlay->backing_file : NULL;
+        bs = bs ?: bdrv_find_active(base_bs);
+    }
+
     if (!bs) {
-        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        error_setg(errp, "Could not find active layer");
         return;
     }
 
@@ -1892,15 +1924,24 @@ void qmp_block_stream(const char *device, bool has_base,
         return;
     }
 
-    if (base) {
+    if (has_base) {
         base_bs = bdrv_find_backing_image(bs, base);
-        if (base_bs == NULL) {
-            error_set(errp, QERR_BASE_NOT_FOUND, base);
-            return;
-        }
+        base_name = base;
+    }
+
+    if (base_bs == NULL && (has_base || has_base_node_name)) {
+        error_set(errp, QERR_BASE_NOT_FOUND, base);
+        return;
+    }
+
+    /* Verify that 'base' is in the same chain as 'bs', if 'base' was
+     * specified */
+    if (base_bs && !bdrv_chain_contains(bs, base_bs)) {
+        error_setg(errp, "'device' and 'base' are not in the same chain");
+        return;
     }
 
-    stream_start(bs, base_bs, base, has_speed ? speed : 0,
+    stream_start(bs, base_bs, base_name, has_speed ? speed : 0,
                  on_error, block_job_cb, bs, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
diff --git a/hmp.c b/hmp.c
index ccc35d4..42fa79e 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1172,8 +1172,8 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
     const char *base = qdict_get_try_str(qdict, "base");
     int64_t speed = qdict_get_try_int(qdict, "speed", 0);
 
-    qmp_block_stream(device, base != NULL, base,
-                     qdict_haskey(qdict, "speed"), speed,
+    qmp_block_stream(true, device, base != NULL, base,
+                     false, NULL, qdict_haskey(qdict, "speed"), speed,
                      true, BLOCKDEV_ON_ERROR_REPORT, &error);
 
     hmp_handle_error(mon, &error);
diff --git a/qapi-schema.json b/qapi-schema.json
index 899beec..b93f21e 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2600,9 +2600,18 @@
 # On successful completion the image file is updated to drop the backing file
 # and the BLOCK_JOB_COMPLETED event is emitted.
 #
-# @device: the device name
+# @device:        #optional The device name.  Optional only if @base-node-name
+#                           is used.
+#
+# For 'base', either @base or @base-node-name may be set but not both. If
+# neither is specified, the entire chain will be streamed into the active 
image,
+# and the chain will consist of a single image (the current active layer) with
+# no backing file.
 #
-# @base:   #optional the common backing file name
+# @base:           #optional the common backing file name
+#
+# @base-node-name: #optional the block driver state node name of the
+#                            common backing file.  (Since 2.1)
 #
 # @speed:  #optional the maximum speed, in bytes per second
 #
@@ -2616,8 +2625,8 @@
 # Since: 1.1
 ##
 { 'command': 'block-stream',
-  'data': { 'device': 'str', '*base': 'str', '*speed': 'int',
-            '*on-error': 'BlockdevOnError' } }
+  'data': { '*device': 'str', '*base': 'str', '*base-node-name': 'str',
+            '*speed': 'int', '*on-error': 'BlockdevOnError' } }
 
 ##
 # @block-job-set-speed:
diff --git a/qmp-commands.hx b/qmp-commands.hx
index c10391c..8ee87f2 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -979,7 +979,7 @@ EQMP
 
     {
         .name       = "block-stream",
-        .args_type  = "device:B,base:s?,speed:o?,on-error:s?",
+        .args_type  = 
"device:B?,base:s?,base-node-name:s?,speed:o?,on-error:s?",
         .mhandler.cmd_new = qmp_marshal_input_block_stream,
     },
 
-- 
1.8.3.1